CrMoV合金钢的微动疲劳实验研究

本文利用一种自行设计的微动疲劳实验装置研究CrMoV合金钢的微动疲劳特性。作者研究了接触压力对材料微动疲劳寿命的影响规律,得到了研究条件下CrMoV合金钢的接触压力阈值。当接触压力较小时,微动桥压块与试件表面间有相对滑动,微动疲劳寿命随接触压力的增加快速下降;当接触压力达到或超过阈值62.5MPa时,微动疲劳寿命达到最低值并不再随接触压力的增加而下降。本文给出了CrMoV合金钢在接触压力为225MPa的微动疲劳曲线和零接触压力(纯)疲劳曲线,并给出微动疲劳强度与常规疲劳强度的关系,分析了微动疲劳破坏的微观机理。

Experimental Study of Fretting Fatigue Behavior of CrMoV Alloy

Fretting fatigue tests of CrMoV alloy were conducted on a self-designed fretting fatigue setup. The effect of contact pressure on fretting fatigue life of the alloy was studied, and the contact pressure threshold (62.5MPa) of CrMoV alloy was obtained under experimental condition. Finally, SEM observations were performed for fracture surface and contact surface. Micro mechanism of fretting fatigue is discussed. Relative sliding movement was observed on the contact surface and multi fretting fatigue cracks were initiated at different position for the fretting fatigue test with contact pressures of lower than 62.5MPa. When the contact pressure is larger than 62.5 MPa, the relative sliding movement is very small and the fretting fatigue crack initiation is concentrated in a very small region. It is shown in this study that fretting fatigue life decreases rapidly with contact pressure increasing until it is equal to or higher than the threshold value of 62.5MPa. Afterwards, the fretting fatigue life reaches minimum value, and keeps constant with contact pressure increase. Both fretting fatigue curve with a contact pressure of 225MPa and the fatigue curve without contact pressure (pure fatigue) were obtained respectively, and the relation between fretting fatigue strength and pure fatigue strength was obtained.